Stan,
Thanks for posting up the local freqs!
I do occasionally tune in to longmont muni or the longmont regional ATC.
As Dave explained, the air bands are VHF frequencies but they are AM modulated. Most HAM VHF is FM, CW, or SSB mode (primarily FM). Your radios need to have both the extended receive and AM modulation, many of the radios will auto switch the mode depending on frequency but you may need to change some settings. Seems that a lot of the 2M only radios don't have extended receive but many dual banders do.